CELL

Which organelle is responsible for producing energy (ATP) in eukaryotic cells?

• Nucleus

• Chloroplast

• Mitochondrion

• Ribosme

Answer explanation

A mitochondrion is a membrane-bound organelle found in most eukaryotic cells that is often called the "powerhouse of the cell". Its main function is to generate chemical energy in the form of adenosine triphosphate (ATP) through cellular respiration.

What is the primary function of ribosomes in a cell?

• Protein synthesis

• Energy production

• Cell division

• DNA replication

Answer explanation

Ribosomes are cellular factories for protein synthesis, reading instructions from messenger RNA (mRNA) to link amino acids together in a specific sequence. Composed of ribosomal RNA (rRNA) and proteins, each ribosome consists of two subunits that assemble on an mRNA molecule to initiate protein production.

Which structure regulates the entry and exit of substances in and out of the cell?

• Plasma membrane

• Nucleus

• Cell wall

• Cytoplasm

Answer explanation

The plasma membrane's primary function is to act as a selectively permeable barrier, regulating the movement of substances into and out of the cell to maintain a stable internal environment. It also provides protection, facilitates cell recognition through molecular markers, supports cell signaling via receptor proteins, and anchors the cell's cytoskeleton.  

What is the role of the endoplasmic reticulum in eukaryotic cells?

• Genetic information storage

• Protein and lipid synthesis

• Energy production

• Waste removal

Answer explanation

The rough endoplasmic reticulum (RER) is essential for protein synthesis; ribosomes attached to its surface translate mRNA into proteins destined for secretion, the cell membrane, or other organelles. These newly synthesized proteins are then folded, modified, and checked within the ER's lumen before being transported via vesicles to other cellular locations, such as the Golgi Apparatus for further processing or delivery.

What is the function of the Golgi apparatus in a cell?

• Photosynthesis

• Cellular respiration

• DNA synthesis

• Protein modification and packaging

Answer explanation

The Golgi apparatus functions as the cell's "post office," modifying, sorting, and packaging proteins and lipids for their final destinations. It receives molecules from the endoplasmic reticulum , processes them through a series of flattened sacs called cisternae, and then packages them into vesicles, for transport to lysosomes, the cell membrane, or for secretion out of the cell. The Golgi also synthesizes complex polysaccharides in plant cells and plays a role in ion homeostasis.  

Which component of the cell is responsible for maintaining its shape and structure?

• Endoplasmic reticulum

• Nucleus

• Cell membrane

• Cytoskeleton

Answer explanation

The cytoskeleton provides a physical framework that helps maintain Golgi shape, move Golgi-derived vesicles, and integrate various cellular signals for proper protein sorting and delivery to their cellular destinations. 

What is the primary role of lysosomes in eukaryotic cells?

• Energy production

• Digestion of waste materials

• Protein synthesis

• Storage of genetic information

Answer explanation

Lysosomes function as the cell's digestive and waste disposal system by using potent enzymes to break down macromolecules (proteins, lipids, carbs, nucleic acids), worn-out cell parts, and engulfed substances like viruses and bacteria. They maintain cellular homeostasis and remove waste, while also playing a role in programmed cell death and cellular signaling.  

What is the function of the plasma membrane in eukaryotic cells?

• Cell communication

• Energy production

• Regulation of substance entry and exit

• Storage of nutrients

Answer explanation

The plasma membrane's primary functions are acting as a selective barrier to control substance transport, providing protection for the cell, facilitating cell signaling and communication, and performing cell recognition and adhesion.

Which organelle is involved in the synthesis of lipids?

• Mitochondrion

• Ribosome

• Golgi apparatus

• Smooth endoplasmic reticulum

Answer explanation

Lipid synthesis, primarily occurs in the endoplasmic reticulum (ER) (especially the smooth ER) and involves converting nutrient-derived acetyl-CoA into fatty acids.

What is the primary role of the nucleus in a cell?

• Cellular respiration

• Protein synthesis

• Storage of genetic material

• Energy production

Answer explanation

The primary functions of the nucleus are to store, protect, and copy the cell's DNA, acting as the cell's control center by regulating gene expression and coordinating cellular activities like growth, metabolism, and reproduction (cell division). It also contains the nucleolus, which is responsible for producing ribosomes, essential components for protein synthesis.